Recently, it is required to reduce a manufacturing cost for manufacturing a semiconductor power device. Specifically, the semiconductor power device is suitably used for an inverter of an automotive vehicle. To reduce the manufacturing cost of the power device, a method for decreasing dimensions of the power device and for decreasing the number of parts in the power deice is provided. In this case, improvement of heat radiation from a semiconductor chip is necessitated. This is because heat generation of the power device becomes larger since the semiconductor power device such as an IGBT (i.e., an insulated gate bipolar transistor) or a MOSFET (i.e., a metal-oxide semiconductor field effect transistor) has high withstand voltage and large capacity of current flow. Specifically, in case of reducing the dimensions of the device and reducing the number of the parts in the device, it is much required to improve the heat radiation of the device.
A package type semiconductor device disclosed in Unexamined Japanese Patent Application Publication No. H13-156225 (which corresponds to U.S. Pat. No. 6,703,707-B1) can reduce heat resistance of a power device so that improvement of heat radiation of the device is performed. In the package type semiconductor device, a semiconductor power device is formed on both of a semiconductor chip. A pair of heat sinks is bonded to both sides of the semiconductor chip through a solder layer. Thus, the heat generated in the power device can be radiated from both sides of the semiconductor chip so that the heat radiation is improved.
However, in the device, a gate runner as a gate wiring layer may short with an emitter electrode, i.e., a main electrode, disposed on a principal surface of the device. Specifically, when the device is used in a temperature range between −65° C. and +150° C., a thermal stress is generated in the main electrode such as an emitter electrode and a backside electrode, which are disposed on both sides of the device. This stress is caused by a difference of thermal expansion coefficient between a heat sink and the device or between a metal block and the device. Here, the heat sink and the metal block are disposed on both sides of the device for radiating the heat generated in the device. Since the thermal stress is generated in the main electrodes, a strain is accumulated in the electrodes. Thus, the main electrode is damaged in a horizontal direction of the device, i.e., in a direction parallel to a substrate of the device so that the main electrode contacts the gate wiring layer. Thus, the main electrode and the gate wiring layer may short. Thus, the device does not work appropriately.